In order to elucidate the structure and function of the human fgr proto-oncogene, studies are directed toward cloning and nucleotide sequence analysis of human c-fgr cDNA as well as identification of its translational product. Several overlapping c- fgr cDNA clones were isolated from a normal mononuclear cell cDNA library. Nucleotide sequence analysis revealed an open reading frame of 529 codons in length. Both antibodies directed against peptides representing amino and carboxy terminal regions of the predicted c-fgr protein specifically immuno-precipitated a 55-kd protein from lysates of COS cells transfected with an expression vector containing the entire c-fgr cDNA open reading frame.